In this series we're building the software of a Mars Rover, according to the following specifications. It allows us to practice the followings: Monolithic Repositories (MonoRepo), Command / Query Responsibility Segregation (CQRS), Event Sourcing (ES) and Test Driven Development (TDD)

We've already developed the first use case about landing the rover on mars, and the second one about driving it. We're now developing the last one, requesting its location. [...] In this article we're going to create a new package for the geolocation value objects (Location, Coordinates and Orientation).

He starts off by creating the geolocation package and its matching composer.json file. He then creates the phpspec configuration for the package and commits this initial version. He pulls this new package into the larger current codebase and makes an update to the overall phpspec configuration to run its tests. With that in place he updates two related packages, location and navigation, to include the new library before integration (coming in the next part of the series).